Banner Ad 1

Request for comment - ballast system

Place for general submarine conversation

Postby fbradasc » Thu Aug 28, 2003 10:39 am

Hi all,
could this ballast system work ?

Image

1) The water pump, which mustn't be tight, could be a simple propeller inside a duct (the L duct in the drawing) and should have the power:
- when submerging: to lift the water up to the top of the sail through the flooding line (red hoses), the air will escape through the venting line (blue hoses)
- when surfacing: to suck the water from inside the M.B.T. through the flooding line and consequently the air from the snorkel will go inside the M.B.T. through the venting line

2) WSW1 and WSW2 are wather switch used to detect when the pump must be switched off:
- if the boat is completely surfaced both WSW1 and WSW2 are OFF:
- if the boat was surfacing switch off the pump
- if need submerging then switch on the pump to submerge

- if the boat is completely submerged both WSW1 and WSW2 are ON:
- if the boat was submerging switch off the pump
- if need surfacing then switch on the pump to surface

- during submerging or surfacing WSW1 is OFF and WSW2 is ON
- the pump must still be powered

3) The M.B.T. should be like a free flooding area (so it mustn't support high pressures), but the flooding line which rise up to the sail (it must be, however, above the surfaced draught line) will prevent the water to enter inside it.

4) When the M.B.T. is completely flooded the boat must still have the top of the sail (the top of the snorkel) above the water level to be able to surface

Advantages:

1) It doesn't requires a powerful and water tight pump
2) It doesn't requires valves, the flooding line passing above the draught line, should prevent the water to enter inside the M.B.T. when the boat is surfaced
3) The M.B.T. can have any shape so can be put outside the WTC

Disadvantages:

1) It MUSTN'T be used to achieve a neutral or negative buoyancy. Use a little trim tank to fine tune the buoyancy (a piston tank, a membrane ballast tank or a bellow ballast tank) but remember to empty this trim tank before switching on the pump of the M.B.T.

...

Suggestions ?
Comments ?
I discovered the warm water ?

Thanks
User avatar
fbradasc
Registered User
 
Posts: 26
Joined: Fri Feb 21, 2003 12:29 pm
Location: Torino, ITALY

Postby smwarships » Mon Sep 01, 2003 6:00 pm

Hello ,
I am working on a ballast tank system right now and I am
thinking about using 2 winshield washer pumps to fill my
ballast tank which will vent through a brass tube and out
through the conning tower .
The windshield pumps are gear driven and when shut off
the do not allow water to flow back out . The motors have
their own sealed containers so the pumps can be put in the
free flood area .

Any thoughts or suggestions ? ???

Darle
User avatar
smwarships
Registered User
 
Posts: 105
Joined: Sat Feb 22, 2003 12:17 am
Location: Morning View,KY

Postby dietzer » Mon Sep 01, 2003 8:56 pm

fbradasc wrote:2) WSW1 and WSW2 are wather switch used to detect when the pump must be switched off:
- if the boat is completely surfaced both WSW1 and WSW2 are OFF:
- if the boat was surfacing switch off the pump
- if need submerging then switch on the pump to submerge

- if the boat is completely submerged both WSW1 and WSW2 are ON:
- if the boat was submerging switch off the pump
- if need surfacing then switch on the pump to surface

- during submerging or surfacing WSW1 is OFF and WSW2 is ON
- the pump must still be powered

Hello,

It's not clear to me whether WSW1/2 are simply switches or whether they are valves.

It seems to me that without some kind of valve, your MBT will lose air when submerged, and result in completely full MBTs. Was that the intent ?

Carl
Carl Dietz
SC#2504
User avatar
dietzer
Registered User
 
Posts: 325
Joined: Fri Feb 21, 2003 11:13 am
Location: SubRon5, Austin, TX

Postby fbradasc » Tue Sep 02, 2003 4:35 am

It's not clear to me whether WSW1/2 are simply switches or whether they are valves.


WSW1/2 are simple water detector (electrical contacts)

It seems to me that without some kind of valve, your MBT will lose air when submerged, and result in completely full MBTs. Was that the intent ?


When submerged the MBT is completely full but the top of the snorkel must be slightly above the water line when you need to surface the boat
User avatar
fbradasc
Registered User
 
Posts: 26
Joined: Fri Feb 21, 2003 12:29 pm
Location: Torino, ITALY

Postby fbradasc » Thu Sep 11, 2003 4:25 am

So then, could this system work ?
User avatar
fbradasc
Registered User
 
Posts: 26
Joined: Fri Feb 21, 2003 12:29 pm
Location: Torino, ITALY

Postby KOEZE » Thu Sep 11, 2003 5:48 am

Of course it can work. Provided:
-your "pump" can overcome the resistance in the tubing
-there is no air in the "flood tubes"
-the airflow to the vent line is unrestricted

Why not use a simple pump or a simple air compressor. These can suplly water or air with a reasonable pressure to overcome the above problems. And if you take a look at the system by Art Broder you can build a similar system without being dependant on outside air.

Just my $0,02 worth.

EJK
You don't stop playing because you get older,
you get older because you stop playing.
User avatar
KOEZE
Registered User
 
Posts: 230
Joined: Thu May 22, 2003 5:55 am
Location: Leeuwarden, The Netherlands

Postby KevinG » Mon Sep 15, 2003 2:20 pm

Hello
What you are proposing is the typical Pump Ballast System. I have used this method very successfully in my DeBoer Skipjack for years. I would suggest removing the water sensing switches and keep the system simple. Use a 3 position momentary switch to operate the pump. (Up-empty, Center off, Down-fill.) In submerged trim the top of the sail is above water and a little water will escape the ballast tank vent port signaling you to shut off the pump. In surfaced trim you will see the boat at the proper waterline and you can often hear the pump suck air. This will signal you to shut off the pump. You want to run the ballast water out completely and hear the gurgling sound or water in the flood line will siphon back into the tank causing the boat to slowly submerge again. This is not a catastrophy. Just use you transmitter to signal the boat to run the pump to vent the tank.

On my boat the submerged trim is half way up the sail and it works great.

Good Luck

Kevin
KevinG
SubCommittee Member
 
Posts: 8
Joined: Mon Apr 07, 2003 12:01 pm

Postby JeffG » Mon Sep 15, 2003 3:45 pm

Seems alot like the system Skip Assay uses in his two finw kits. The ballast system works great. I add a subsafe to blow the ballast in case radio signal is lost. Also from Skip

Jeff Groseth :)
User avatar
JeffG
Registered User
 
Posts: 28
Joined: Tue Mar 11, 2003 2:39 pm
Location: California

Postby bobcowan » Mon Sep 15, 2003 4:08 pm

Try the bladder system. Simplest and most robust of them all. Use a medical IV 'bladder' bag with an automotive windsheild washer pump or preferably a peristaltic pump. This system is closed so you can sit on the bottom and it meters water in and out in such a way that hovering is a breeze. It also has a built in 'sub-safe' because if you lose radio contact or have any other on board mechanical failure pressure will eventually take over forcing water out of the bag and your boat to surface. (this will take a number of agonizing hours). Every system has it's advantages/disadvantages and I have used gas and a piston ballast but returned to the pump/bladder bag this summer with my 1:72 scale Permit to discover simple is best.

Bob Cowan
Bob Cowan
The SubCommittee 2562
User avatar
bobcowan
Registered User
 
Posts: 40
Joined: Thu Mar 13, 2003 2:13 pm
Location: Hamilton, Ontario  Canada

Postby fbradasc » Thu Sep 18, 2003 6:27 am

I would suggest removing the water sensing switches and keep the system simple.


Kevin, I thought to use a micro controller to start/stop the pump for surfacing/submerging, so, from the R/C I need only one push button to command the sub for the diving operations.

Try the bladder system


Bob, the bladder system must be designed to support high pressures for the pump and the hoses, also, lesser the pressure higher the volume occupied by the air pressure bottle inside the WTC. It's right ?

Thank you all
User avatar
fbradasc
Registered User
 
Posts: 26
Joined: Fri Feb 21, 2003 12:29 pm
Location: Torino, ITALY


Return to General

Who is online

Users browsing this forum: Yahoo [Bot]